Having a wattage readout on a vv regulated device is not a simple thing, especially since there are no off the shelf components for it.

You can go the route of a microcontroller with a digital display, but it's technologically advanced and requires wiring in and working with a microcontroller as well as having programming skills. There's only a few people that have the skills to do that.

What is easily incorporated into a vv regulated device is a voltage reader for displaying input and output voltage. You can then easily calculate watts.

Those watts meters are great for testing breadboarded setups, but to put that in a mod you'd need a huge enclosure for it even if you gutted its case and grabbed just the components. Plus - it needs its own source voltage of ~5v.

Those watts meters are great for testing breadboarded setups, but to put that in a mod you'd need a huge enclosure for it even if you gutted its case and grabbed just the components. Plus - it needs its own source voltage of ~5v.

...To reduce input transients, I would add a low ESR 100uF input cap. If using a main power switch, I'd put it behind the switch so it's already charged when the converter is energized.

Would it be suitable to use one 22uF cap, or 2x22uF caps, on input with the OKR-T10 board? Is there harm in adding too much capacitance on the input as there is on the output? Was just wondering.

For input cap, the OKR-T10 datasheet says...

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For best performance, we recommend installing a low-ESR capacitor immediately adjacent to the converter’s input terminals. The capacitor should be a ceramic type such as the Murata GRM32 series or a polymer type. Initial suggested capacitor values are 10 to 22 ?F, rated at twice the expected maximum input voltage. Make sure that the input terminals do not go below the undervoltage shutdown voltage at all times. More input bulk capacitance may be added in parallel (either electrolytic or tantalum) if needed.

The tantalum polymers are pretty nice caps, they have excellent characteristics. The cost and size for value ratio is really good with them. Though the disadvantage with them is they are not as robust as the cermic ones. They are plorized and suffer hideous failures when hit with negative voltage spikes. I know since I've blown them up on the bench before. They explode like a firecracker. Nothing wakes you up quite like an exploding capacitor.

Anyway, the only problem with too much input capacitance that immediately comes to mind is that it can cause input voltage to ramp up too slowly. It depends on the part, but most integrated circuits have a limitation there. Otherwise, more is better. You probably would not be able to add too much input capacitance for what you would want to practically fit in an e-cig mod. Though in some cases, other characteristics can beat out higher capacitance if there's a huge difference between one cap and another. For example, a 100uF MLCC cap would actually perform better than a 1000uF standard tantalum cap at higher frequencies due to the much lower ESR of the ceramic cap.

The Tantalum caps make out in my usage as a perhaps smoother vape than the low esr radial capsThey both are fast per se' when dry burning a coil its instant, but theres a twist in the recipe with the Tants its enough to be noticed. Both vapes are amazing but right now as a novice in hotter vapes they are what I prefer dialing in and out.. Edit:::;; with a single coil, with a dual coil the radial caps definitely. I had forgot about that experiment. Burns twice as much juice, I do not dual often...

Standard tantalums are falling out of favor. A decade or two ago they were popular as a small footprint solution for higher capacitance values, but MLCC caps have surpassed them in some cases. The technical advancement for MLCC caps has really taken off in the last decade. Standard tantalums still go higher in capacitance value and voltage ratings, but you can use an array of MLCCs to get the values you need and it may not be any more expensive or use any more circuit board real estate.

Standard tantalum capacitors have an awful ESR characteristic, like several Ohms compared to a few hundredths of an Ohm for an electrolytic and a few thousandths of an Ohm for an MLCC cap. That's comparing an electrolytic with a higher voltage rating and an MLCC cap in one the larger footprints. ESR goes up for smaller MLCCs like the 0805 and 0603 sizes. ESR goes up for electrolytics when voltage ratings fall under ten Volts. Though it's not a huge amount in either case, less than an order of magnitude.

Standard tantalums can still be useful for low frequency applications, but for the frequencies utilized by the switching regulators we typically use, they're pretty worthless. Now tantalum polymers are something entirely different. Those are much better performers and compete nicely with MLCC caps. If I was not going to use an MLCC cap with a switching regulator, I would use a tantalum polymer. I actually did use them for one one of the early mods designs I did. They do have their advantages like controlled ESR and very nice stability over temperature and voltage. The negatives are they're bit larger, they're polarized, and have lower ripple tolerance. Also, they can only be driven within about 80% of their rating, in other words, they're over-rated. MLCC caps are typically under-rated and can usually handle moderate overloading without issue.

Hello all! I had a question about the OKR t10 chip, if I may. I have dabbled in electronics for awhile and familiar with ohms law, voltage and current, wiring, soldering etc. Been reading through the forum here and i have A LOT to learn but I am willing. I have a few mechs, a couple Vamos and am comfortable rebuilding my own coils. I have been wanting to make my own mod and decided to use the OKR t10. I have it all wired up and when i went to test voltage output to my atomizer its output is 7volts! (I am using 2 18650 efest 30 amp batteries wired in series.) My potentiometer is a 200 ohm and I measure a sweep from 0 ohms to 185 ohms. Voltage when firing goes from 7 to 7.8ish when dialing the pot and watching at the atomizer. I put an atomiser at 1.8 ohms on to load the circuit and it hits like a truck and I can't turn it down. I made sure not to hold the iron on the t10 board for more than a few seconds and presoldered every wire and pin. Should I just solder another chip in? I know the diagram adds a 200 ohm resistor, which I didn't do to have maximum adjustability. Thank you all so much in advance for the help, hopefully I can pass it on someday.

Ugh, I'm sorry guys. Classic "didnt read the spec sheet deep enough turns out I do need the 200ohm resistors. The scaling was backwards in my head for some reason. I'm sorry!

That is close to exactly what your output would be if you used a 0 to 185 ohm pot. If you look at the datasheet RTRIM formula 7 volts output with the pot max'd at 184.43K ohms and 7.8v for 0 ohms. Use the fixed 200 ohm in series.

As far as fuses, I don't know. Honestly I haven't put one in my mod because the chip has short circuit protection, if a wire were to short before the chip however, probably not a bad idea. As for a voltmeter, I check voltage in parallel with the atomiser connector. Series would be a good example for an ammeter install tho. In series the meter would also have to take the current draw of the atomiser installed. I would speculate if you wired a voltmeter to the ground of the battery and put a 2 way switch and split the positive wires, put one on the battery positive and the other on the atomizer positive you can select which voltage you want to monitor. With the switch in one position, the voltmeter would show battery pack voltage and in the other position it would read atomiser voltage.

The type of fuse is a PTC (polymeric positive temperature coefficient) which is a resetable type, in other words, it trips when there's a fault and returns to a low resistance state when the fault clears. They are widely available and inexpensive. You can use the leaded type or the surface mount type. There's a thread here with a long discussion about PTC fuses which should be a help for you; http://breaktru.com/smf/index.php/topic,723.0.html

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what kind of current am i expecting to draw from the batteries and what should the fuse be rated for.

For the OKR-T/10, maximum output power is 50W so maximum input power would be 60W providing a liberal margin for losses. Minimum battery voltage is 6V with two cells in series so maximum input current is 10A. For PTC fuses, you typcially use the "hold" rating equal to maximum input, but you can go under an amount since trip currents are typically around double the hold current.

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also if i wanted a voltage meter to display my output can i just wire the voltmeter in series with the atty connector

You can get 1S-6S voltmeters for hobby applications that are commonly used in mods. They're cheap and you can find them on eBay or at HobbyKing.I almost commented on the series-parallel thing, but then I saw you corrected it, but yeah, voltmeters in parallel, ammeters in series.

Yes, a fuse is recommended in the data sheet for the OKR-T/10. Primarily it's for reverse polarity protection since the switching regulator provides over-current protection through its control circuits. In any case, it's generally a good idea to fuse anything powered by a Li-Ion battery since a current fault can cause the cell to overheat and catch fire. Even if it's not a matter of safety, current faults can damage things that might otherwise be repairable.

Kortt, if I may ask, how do you make the bezel or lense for your voltmeters like the one linked? I'm pretty careful with my cuts but I see mods here with gorgeous LCD/led panel meters and I haven't a clue shown its done. Thanks in advance for any info!

Kortt, if I may ask, how do you make the bezel or lense for your voltmeters like the one linked? I'm pretty careful with my cuts but I see mods here with gorgeous LCD/led panel meters and I haven't a clue shown its done. Thanks in advance for any info!

Yes kortt. Those are the meters that I have been using. I like them better than the 1s6s type which takes some time to pulse through 6 cells before reading the single cell. The advantage of the 1s6s is that you can read multiple batteries without needing a switch. For instance you can wire the first (+) for output voltage and second (+) for battery voltage.

Question regarding a voltage cutoff for the OKR. I want to make a simple circuit to ground pin 1 when voltage drops below 6.5 volts. I know I could make something to close a switch above a certain voltage but having to have it close at a low voltage is where my electronics theory is poor. I don't even need an answer to the problem directly. Can someone point to a theory lesson that may improve my own knowledge in doing something like this? I want to learn, not be spoon fed thank you all for your patience and responses.Oh, and I read somewhere, maybe one of mamu's posts that I would need a resistor across 2 pins to prevent the box to continually fire? I didn't see it in the schematic. Thanks again!

Question regarding a voltage cutoff for the OKR. I want to make a simple circuit to ground pin 1 when voltage drops below 6.5 volts. I know I could make something to close a switch above a certain voltage but having to have it close at a low voltage is where my electronics theory is poor. I don't even need an answer to the problem directly.[/b] Can someone point to a theory lesson that may improve my own knowledge in doing something like this? I want to learn, not be spoon fed thank you all for your patience and responses.Oh, and I read somewhere, maybe one of mamu's posts that I would need a resistor across 2 pins to prevent the box to continually fire? I didn't see it in the schematic. Thanks again!

Question regarding a voltage cutoff for the OKR. I want to make a simple circuit to ground pin 1 when voltage drops below 6.5 volts. I know I could make something to close a switch above a certain voltage but having to have it close at a low voltage is where my electronics theory is poor. I don't even need an answer to the problem directly. Can someone point to a theory lesson that may improve my own knowledge in doing something like this? I want to learn, not be spoon fed thank you all for your patience and responses.Oh, and I read somewhere, maybe one of mamu's posts that I would need a resistor across 2 pins to prevent the box to continually fire? I didn't see it in the schematic. Thanks again!

It might be hilarious, but it's valid. I have the same sentiment, I want to learn this stuff too and would prefer to have the knowledge to understand it over just building from a pre-made schematic. That is one of the reason I do my "kindergarten" style wiring diagrams. It helps me understand things in my own way.

It might be hilarious, but it's valid. I have the same sentiment, I want to learn this stuff too and would prefer to have the knowledge to understand it over just building from a pre-made schematic. That is one of the reason I do my "kindergarten" style wiring diagrams. It helps me understand things in my own way.

No what he said about answering the post I even underlined and bolded it.

How a zener diode works as a low voltage cutoff is that it allows current to flow IF the input voltage is above the zener's breakdown voltage. When input voltage gets below the zener's s breakdown voltage it shuts off current flow which shuts off the converter from firing.

For more info on how a zener diode works, there's several online tutorials available on electronic sites - just google how does a zener diode work or something along those lines.

Thank you all for your responses! Now while I understand how a zener diode functions (always allows current flow in one direction, refuses current flow in opposing direction until a certain voltage/ saturation voltage is met), what I guess I'm confused about is the OKR circuitry. Pin 1 needs to be grounded to shutoff the converter. Does pin 1 use a certain voltage that gets pulled down when grounded telling the chip to not fire? If that's so, when the zener diodes saturation point drops and it stops flow of current in that direction, the path open is the one to ground through the resistor? I'm sorry I'm so new at this.

The enable pin uses a logic level input to determine the on or off state. Logic levels are typically .3 V and below for a 0 (disabled) or .6 Volts and above for a 1 (enabled). There are different logic levels employed, for example TTL logic has higher thresholds, but CMOS logic is by far most common and those have the lower threshholds I mentioned.

Zener diodes rely on the reverse breakdown characteristic of a junction diode. When voltage is below the breakdown voltage, no current flows other than a small leakage. When voltage is higher than the breakdown voltage, an "avalanche" condition occurs across the diode's junction. This results in higher current flow as the diode tries to maintain the breakdown voltage.

The resistor is required to limit current flow when the diode junction is in an avalache condition. At the resistor, voltage will be the source minus the breakdown voltage when the diode is conducting (source above breakdown voltage) or zero when the diode is not conducting (source below breakdown voltage).

I totally agree about the statement made before, it's better to take the time to understand what you're doing than to just copy a schematic blindly. Besides, electronics is a really interesting study anyway, at least it's always been for me.

Simplified drawings can be handy, but a hobbyist really needs to get comfortable with using a proper schematic. When circuits get more involved, there's just no way around that.

That was an excellent description Craig, I appreciate the time you spent typing all that out. I see much more clearly now how that functions! I think I need a breadboard to experiment with the circuits and maybe gain a more hands on knowledge of precisely how everything works.

Also, mamu, I was aiming for 6.5 volt cutoff because I have always read individual cell voltage shouldn't drop below 3.2 volts, I figured for errors sake with an individual cell, 6.5 would suffice. Is there any harm in actually going to 6 volts before the circuit shuts down? I realize the voltage at rest is higher than under load. Just trying to be cautious about proper battery care.

Visus, I am sorry, I didn't mean for it to be worded that way. I know everyone on this site has a tremendous amount of experience and knowledge, much more than myself. I just simply didn't want an answer or schematic. I need reading material to learn what I am doing. I apologise if my post came off like that.

Curious when the economy was good, courses we're offered for free on just about everything you can think of hobby and professional. It was called the learning annex. They have moved to the web, as sponsors are to few to keep the doors open these days. I really miss them my ol lady stayed a block away from their building and I always wanted take an electronics course but never got around to it.

I like schematics myself and data sheet its my daily job reading blueprints but our schematics and legends are kindergarten compared to electronic sheets, once those open up in the brain it moves to the mechanical side and only by doing will the mechanical side become awesome.. Its why Ironman is the mechanic he is all hands on, all do, at his point of electronics implementation and nothing is impossible..

Thank you for the response. I've always wanted to take an electronics course but saw that as more of a hobby and decided on vehicle repair as a trade. (I may have mentioned I'm not the brightest crayon in the box) The grass is always greener.. I know a little about electrical, HVAC, hydraulics, electronics, networking, mechanical etc but haven't mastered the one I am truly interested in. Electronics. Not even close. I look forward to absorbing as much as possible and maybe someday creating my own circuits to solve my own problems as well as pass it on.

...Also, mamu, I was aiming for 6.5 volt cutoff because I have always read individual cell voltage shouldn't drop below 3.2 volts, I figured for errors sake with an individual cell, 6.5 would suffice. Is there any harm in actually going to 6 volts before the circuit shuts down? I realize the voltage at rest is higher than under load. Just trying to be cautious about proper battery care.

The 2C round cells are typically 2.7V, but I've seen some that are as low as 2.5V. The LiPos and high drain round cells are all flat at 3.0V. The minimums for a cell include the voltage sag you get under load. For the lower drain cells, the drop under load can be considerable. For a high performance cell with really low internal resistance like a 20C LiPo or one of the ultra-high drain 18650s, there's not much drop even under heavy load so a voltage can be used across the board with those.

You get the absolute most out of a cell if you take it down to the limit, but once you get into the part of the discharge curve that falls off sharply there's not much to be gained. There's really no considerable amount of charge in the last third of a Volt. It's better not to stress the cell for the little you can get out of it. If you take a high drain cell to 3.3V, you're good. For those I generally do a minimum of 3.3 to 3.4 for open circuit voltage and 3.1 to 3.2 under load.

You want your Zener to have a voltage spec a little lower than the cutoff voltage since the logic will toggle low a small amount above zero volts. A 6V Zener should get you close, but there's wiggle room in the logic levels so it can vary depending on the regulator. It also depends on the resistor value since higher values can cause offsets due to leakage currents. You want a higher value resistor to minimize power loss, but if it's too high, it can cause an offset level above logic low.